The present invention relates to a lock for trigger safety to be used in firearms triggers and a trigger assembly that contains the trigger safety lock, to be used particularly in hand held pistols. Preferably, the invention is to be applied, and is an improvement, to the safety mechanism used in pistols with brand GLOCK®, which will be called, for simplicity, from now on this document as the GLOCK® safety mechanism.
The trigger safety lock of the present invention allows for adding safety features to the known GLOCK® safety mechanism, particularly in those cases in which the user is forced to walk through places of difficult access while holding the pistol in his hand. Obstacles such as figs, bushes, or any kind of interfering elements that may be found in countryside or city environments may get caught in the trigger and cause accidental shots.
The GLOCK® safety mechanism is one of the mostly used safety features in firearms. In these mechanisms, apart from the internal safety mechanisms, the pistols also show a secondary trigger, also called trigger safety member, formed by a pivotally mounted member placed inside a slot made in the main trigger, which protrudes at the lower front portion of the main trigger. The trigger safety member has a rear protruding blocking portion which abuts against the wall of the hand grip placed right behind the trigger when the pistol should be locked.
Although the GLOCK® mechanism is known worldwide to be one of the safest and most effective one, it may still be improved. Since the main trigger and the secondary trigger are both housed very nearby, and both acting in the same direction when the user pulls them for shooting, any foreign object that accidentally gets into the trigger guard housing and getting in the way of the trigger assembly may press on both elements and produce an unwanted shot.
Most hand weapon manufacturers have models designed for police or military use. These weapons usually have a strap engaged to the rear part of the hand grip. On several occasions, police o security personnel have to run with the weapon in their hand and a simple stumble may cause the weapon to fall several feet away from them, unless they use the strap. However, when doing so, this element has also shown to be quite dangerous if the weapon uses the GLOCK® safety mechanism because the strap gets tangled in the trigger mechanism and causes accidental shots when the weapon is placed in its holster.
Another way of improving the safety of GLOCK® mechanism by adding a sliding type element or lever acting mechanism at the side of the pistol, like the one used in the old Colt® 45 pistols would not be easily feasible, because it would imply doing major and costly amendments to the weapon.
Other weapons such as the old Remington® rifles of the early years of the XX century and several other caliber 22 rifles had a safety mechanism placed behind the trigger guard consisting of a cylinder with a groove that prevented the trigger to slide to the back when the rifle was locked. Nowadays, several repetition ammunition shotguns still use this old mechanism. However, none of these seems to be useful for improving the GLOCK® safety mechanism.
The safety lock of the present invention is an improvement to the GLOCK® secondary trigger safety and was designed to be operated from the side of the trigger with a transverse movement to avoid any possible accidental locking or unlocking engagement while the pistol is out of its holster. Attempts for amending the GLOCK® trigger assembly for letting it work in an improved way failed. A careful analysis of the trigger manufactured by GLOCK® shows that it is too thin for making a side through-hole for inserting a locking pin of suitable diameter (around 4.0 mm) or making a 2.00 mm notch for letting the pivoting safety member (secondary trigger) be lowered for acting in the way the present invention does. Other issue in this trigger assembly that should be solved is the fact that the elastic member that biases the GLOCK® safety member (secondary trigger) for returning it to an initial position after being triggered is an integral part of the member itself. The whole safety member, including its elastic biasing member, is made of acetal resin, a low cost polymer that is not adequate for heavy duty, long term, alternative stress. Acetal resin tends to lose flexibility in the long term and may finally break due to material fatigue to bending stress. Therefore this biasing member was replaced in the improved safety member by a biasing helicoidal spring, preferably made of stainless steel. However, a biasing member made of polyurethane may also be an acceptable alternative solution since this material is highly resistant to bending fatigue.
In the first preliminary prototypes, a cedar wood trigger was used, with its lower portion thickened for achieving better resistance after doing the side hole for inserting the locking pin, and a thicker safety member made of aluminum. The first prototypes also included a locking pin made of hard aluminum and, although these materials proved to be not adequate for the invention, they allowed to prove that the design may be carried out.
A further prototype included an electrolytic bronze trigger which was useful for making a die that was further used for injecting several prototype triggers made of acetal resin, i.e. the same material as the one used by the manufacturer of the GLOCK® pistol. In this prototype the locking pin was made of Teflon®, a polymer of very good sliding features. However, making such small elements with sufficient precision using the turning lathe on this material proved to be cumbersome because the machine tends to bend the finished member. In an attempt to overcome this issue a 1 mm thick steel-silver rod was inserted in the Teflon® rod but the whole process proved to be too complicated for industrial purposes, and was finally discarded.
A further prototype was made with a locking pin made of bronze housed in an acetal resin trigger, but this material proved to be not resistant enough to wear-out. In an attempt to avoid wear-out, and for improving the engagement of the locking pin inside the trigger, a pair of synthetic rubber O'Rings were placed in corresponding grooves made on the locking pin's surface, but these O'Rings were torn very soon.
A preferred embodiment of the present invention was finally obtained by using polyurethane for both the trigger and the safety member (secondary trigger). However, since the trigger would have to resist the user's hand triggering pull, it was made with 60 D Shore polyurethane to achieve better flexibility features; on the other hand the safety member was made with 74 D Shore to achieve better rigidity and hardness features. After several tests, it was found that the best material for making both elements proved to be the BASF® polyurethane due to its exceptional endurance properties, and leaving the BAYER® polyurethane as a second choice. The locking pin was made by machining a 4.5 mm 12 L 14 carbon steel rod, an easily obtainable element in most markets, to get a 4.0 mm steel rod and further chroming preferably by electrolytic process, to obtain a chromed steel locking pin.
A highly preferred embodiment includes two protruding ridges made on the surface of the end portions of the locking pin and corresponding grooves made on the inner surface of the trigger for safely keeping the pin engaged in the selected position (i.e. locking or unlocking the trigger). Furthermore, the preferred embodiment also is designed so that the force for locking the pistol is greater than the force required to unlock it. This was done for safety reasons, taking in account that the user may be under great mental stress when he needs to unlock the pistol, while the act of locking it may probably be done in a more relieved state of mind. This is achieved by letting the ridge of the locking side end be slightly higher than the other one.